Hemispheric asymmetries in categorical perception of orientation in infants and adults

Orientation CP is the faster or more accurate discrimination of two orientations from different categories (e.g., oblique1 and vertical1) compared to two orientations from the same category (e.g., oblique1 and oblique2), even when the degree of difference is equated across conditions. Here, we assess whether there are hemispheric asymmetries in this effect for adults and 5-month-old infants. Experiment 1 identified the location of the vertical-oblique category boundary. Experiment 2, using a visual search task with oriented lines found that adult search was more accurate when the target and distractors were from different orientation categories, compared to targets and distractors of an equivalent physical difference taken from the same category. This effect was stronger for targets lateralized to the left visual field (LVF) than the right visual field (RVF), indicating a right hemisphere (RH) bias in adult orientation CP. Experiment 3, replicated the RH bias using different stimuli and also investigated the impact of visual and verbal interference on the category effect. Experiment 4, using the same visual search task, found that infant search was also faster when the target and distractors were from different orientation categories than the same, yet this category effect was stronger for RVF than LVF lateralized targets, indicating a LH bias in orientation CP at 5 months. These findings are contrasted to equivalent studies on the lateralization of color CP (e.g., Gilbert, Regier, Kay, & Ivry, 2005). The implications for theories on the contribution of the left and right hemispheres of the infant and adult brain to categorical computations are discussed.     

皮层电极描记配合立体定向切除癫痫灶

目的 评价皮层电极描记在立体定向切除癫痫灶手术中的应用和价值。方法 对25例以癫痫为首发症状的继发性癫痫患者采用MRI导向下，立体定向环钻开颅，切除病灶前行皮层电极描记，记录有无癫痫波和范围，切除病灶后再次描记，如仍有癫痫波，则在不影响神经功能的基础上将有癫痫波的皮层尽可能切除。结果 25例患者中有19例在切除病灶前记录到棘波、棘-慢波、尖波或尖-慢波，切除后有15例上述癫痫波完全消失，4例仍有散在的少许癫痫波；另有6例患者未记录到癫痫波，但表现为基本的节律异常，切除病灶后好转。25例患者中胶质瘤6例，脑囊虫病5例，蛛网膜囊肿3例，软化灶3例，皮层发育不全2例，血管畸形2例，转移癌2例，炎症1例，胶质细胞增生1例，病灶直径在0．8～4．7cm。手术后24例癫痫发作消失，1例仍偶有癫痫发作，比例能够被口服抗癫痫药物控制。手术后患者无神经功能损害加重。结论 皮层电极描记和立体定向方法相结合，既能明确癫痫灶的范围，又能以微侵袭的方法切除癫痫灶，尤其适用于直径小于4cm的癫痫灶的切除。     

情感韵律加工的单侧化

首先阐述韵律加工的神经机制的相关假说,然后从情感韵律的知觉和产生两方面,回顾大脑半球在情感韵律加工中的单侧化优势的相关研究。大多数研究表明,情感韵律的加工主要在右半球,此外,皮层下组织在情感韵律产生和知觉中起着重要作用。     

Epidemiology of tick‐borne pathogens in the semi‐arid and the arid agro‐ecological zones of Punjab province,Pakistan

Tick‐borne diseases (TBDs) have a large impact on animal health and the livelihood of livestock owners, particularly in developing countries. Although climatic and ecological conditions in Pakistan may favour the transmission of tick‐borne pathogens (TBPs), only a few systematic studies have been carried out on TBPs and the diseases that they cause in this country. To improve our understanding of the distribution of TBPs, 3,807 ticks were collected from ruminants (n = 369) on 108 livestock farms (semi‐arid zone = 36, arid zone = 72) in Punjab Province. After morphological identification ticks were pooled into 405 pools (Hyalomma anatolicum = 300, Rhipicephalus microplus = 89, Hyalomma dromedarii = 9, Rhipicephalus turanicus = 7) based on their species, locality of collection, and the host. DNA from each pool was screened by a Reverse Line Blot (RLB) hybridization assay for the presence of Anaplasma, Ehrlichia, Rickettsia, Babesia, and Theileria species. DNA from at least one TBP was found in 142 (35.1%) pools. Among the positive pools, 91 (64.1%) had a mixed infection with two or more TBPs, whereas 51 (35.9%) pools were infected with a single TBP. The detected pathogens not only included species that were known to be endemic in Pakistan, such as Theileria annulata (6.7%), Theileria orientalis (3.5%), Anaplasma marginale (5.7%), Anaplasma centrale (2.7%), Anaplasma ovis (1.5%), Babesia bigemina (0.7%), and Babesia bovis (0.2%), but also several TBPs that had not been reported to occur in Pakistan before. This included Ehrlichia minasensis (3.2%), an Anaplasma platys‐like organism (1.2%), Babesia occultans (0.2%), and Rickettsia massiliae (0.2%), as well as two previously uncharacterized species: Ehrlichia sp. Multan (18.0%) and Anaplasma sp. (BL099‐6) (2.22%). The pathogenicity of these novel species remains to be examined. This study shows that a much broader spectrum of TBPs is present in Pakistan than previously thought, including several zoonotic pathogens.     

皮层脑电图辅助立体定向下手术治疗颅内钙化灶引起的难治性癫痫

目的研究立体定向下开放式手术联合术中皮层脑电图(ECoG)监测治疗颅内钙化灶性癫痫的手术方法、注意事项及效果。方法 21例颅内单发钙化灶引起的癫痫患者(其中主要功能区钙化灶9例),在立体定向仪导向下,开放直视手术,ECoG监测钙化灶周围皮层脑电活动情况,切除钙化灶后再次ECoG监测,确定致痫灶的范围及处理方式。结果所有钙化灶均被顺利切除。钙化灶区域ECoG监测无明显异常5例,表现为阵发性与动脉搏动相一致的单发性棘慢复合波发放9例,表现为明显癫痫样放电7例。单纯钙化灶切除术14例,钙化灶+周边增生组织+致痫皮层切除术4例,钙化灶切除+功能区致痫皮层低功率电凝热灼术3例。术后ECoG监测发现异常放电消失11例,仍残存轻中度痫样放电5例。无严重并发症。随访6个月～8年,EngelⅠ级16例,EngelⅡ级5例,总有效率100%。结论 ECoG监测是立体定向下手术治疗颅内钙化灶性癫痫的重要辅助手段,能够指导术中采取相应的手术方式切除钙化灶,妥善处理致痫灶,避免过多损伤脑皮层。     

额叶癫癎的致癎灶定位与手术治疗

目的 探讨额叶癫癎的致痴灶定位和手术治疗的策略。方法 分析29例额叶癫癎患者的术前综合定位、术中皮层脑电图监测、术式选择及术后效果的临床资料。结果 影像学检查结合长程视频脑电图监测,可以为12例定位致癎灶;而结合颅内脑电图长程记录,24例可以定位致癎灶,其中包括10例影像学检查阴性的病例。随访1年以上,按照Engel’s效果分级:Ⅰ级13例,Ⅱ级7例,Ⅲ级4例,Ⅳ级5例。结论 影像学检查、长程视频脑电图监测以及颅内脑电图长程记录和术中皮层脑电图监测相结合的综合定位方法,可以提高额叶癫癎的致癎灶定位效果和手术疗效,其中颅内电极记录尤其有助于定位影像学检查阴性病例的致癎灶。     

Functional cerebral asymmetries during the menstrual cycle: a cross-sectional and longitudinal analysis

This study aims at answering two basic questions regarding the mechanisms with which hormones modulate functional cerebral asymmetries. Which steroids or gonadotropins fluctuating during the menstrual cycle affect perceptual asymmetries? Can these effects be demonstrated in a cross-sectional (follicular and midluteal cycle phases analyzed) and a longitudinal design, in which the continuous hormone and asymmetry fluctuations were measured over a time course of 6 weeks? To answer these questions, 12 spontaneously cycling right-handed women participated in an experiment in which their levels of progesterone, estradiol, testosterone, LH, and FSH were assessed every 3 days by blood-sample based radioimmunoassays (RIAs). At the same points in time their asymmetries were analyzed with visual half-field (VHF) techniques using a lexical decision, a figure recognition, and a face discrimination task. Both cross-sectional and longitudinal analyzes showed that an increase of progesterone is related to a reduction in asymmetries in a figure recognition task by increasing the performance of the left-hemisphere which is less specialized for this task. Cross-sectionally, estradiol was shown to have significant relationships to the accuracy and the response speed of both hemispheres. However, since these effects were in the same direction, asymmetry was not affected. This was not the case in the longitudinal design, where estradiol affected the asymmetry in the lexical decision and the figural comparison task. Overall, these data show that hormonal fluctuations within the menstrual cycle have important impacts on functional cerebral asymmetries. The effect of progesterone was highly reliable and could be shown in both analysis schemes. By contrast, estradiol mainly, but not exclusively, affected both hemispheres in the same direction.     

Prediction of Probabilistic Sleep Distributions Following Travel Across Multiple Time Zones

Study Objectives:

To parameterize and validate a model to estimate average sleep times for long-haul aviation pilots during layovers following travel across multiple time zones. The model equations were based on a weighted distribution of domicile- and local-time sleepers, and included algorithms to account for sleep loss and circadian re-synchronization.

Design:

Sleep times were collected from participants under normal commercial operating conditions using diaries and wrist activity monitors.

Participants:

Participants included a total of 306 long-haul pilots (113 captains, 120 first officers, and 73 second officers).

Measurement and Results:

The model was parameterized based on the average sleep/wake times observed during international flight patterns from Australia to London and Los Angeles (global R² = 0.72). The parameterized model was validated against the average sleep/wake times observed during flight patterns from Australia to London (r² = 0.85), Los Angeles (r² = 0.79), New York (r² = 0.80), and Johannesburg (r² = 0.73). Goodness-of-fit was poorer when the parameterized model equations were used to predict the variance across the sleep/wake cycles of individual pilots (R² = 0.42, 0.35, 0.31, and 0.28 for the validation flight patterns, respectively), in part because of substantial inter-individual variability in sleep timing and duration.

Conclusions:

It is possible to estimate average sleep times during layovers in international patterns with a reasonable degree of accuracy. Models of this type could form the basis of a stand-alone application to estimate the likelihood that a given duty schedule provides pilots, on average, with an adequate opportunity to sleep.

Citation:

Darwent D; Dawson D; Roach GD. Prediction of probabilistic sleep distributions following travel across multiple time zones. SLEEP 2010;33(2):185-195.     

Asymmetry of interhemispheric interaction in left-handed subjects

In right-handed subjects the execution of a simple finger-tapping task is associated with an asymmetry of interhemispheric interaction, probably suggesting that the dominant left hemisphere inhibits the right one. The present study investigated the left-handed subjects in order to elucidate whether this asymmetry is related to handedness. Nineteen healthy subjects performed unimanual left, right, and bimanual auditorily paced finger-tapping tasks while neuromagnetic activity was recorded with a 122-channel whole-head neuromagnetometer (MEG). Simultaneously, we recorded activity of the first dorsal interosseus (FDI) muscle of both hands. By using the analysis tool dynamic imaging of coherent sources (DICS), oscillatory activity at alpha as well as at beta frequency within the primary sensorimotor (S1/M1) and premotor (PMC) cortex was localized. As expected, we observed oscillatory coupling between S1/M1 and PMC contralateral to the moving hand. Furthermore, coupling between left PMC and bilateral S1/M1 occurred in each movement condition, suggesting that the left PMC modulates neural activity in bilateral primary sensorimotor cortices independent of the moving hand. Coupling between bilateral S1/M1 occurred more frequently and significantly stronger during the right hand condition. This result demonstrates the same interhemispheric coupling pattern as in right-handed subjects, suggesting that the asymmetry of this interaction is not due to hand dominance. A specialization of the left premotor cortex either for superior motor control per se or for the execution of sequential tasks might account for these results.